For components in organic electronics it is customarily the case that the lower the voltage drop across the transport layers with p- (hole) or n- (electron) conductivity that are contained in these components, the greater the efficiency of the components. This functional relationship is valid especially for organic light-emitting diodes (schematic layer construction represented in FIG. 1) and organic solar cells (FIG. 2). For organic field-effect transistors (FIG. 3), similar relationships apply, and in these cases the efficiency of the injection of charge carriers is dependent, in particular, on the level of the contact resistances. If this can be minimized, an increase is obtained in the effective mobility of the semiconductor. Established in the art, in addition to the use of suitable electrically conducting organic materials, is the introduction into the layers of additional substances whose effect is to increase the intrinsic conductivity of these materials. Depending on the desired purpose, a distinction is made here between p- and n-dopants, which improve the p- or the n-conductivity of transport/contact layers, respectively. The number of n-dopants available for these organic-electronic components is very limited, thereby restricting the design possibilities and present technical performance of organic components. Consequently, in addition to the use of suitable dopants in OLEDs, the utilization of these dopants in field-effect transistors for contact doping, particularly in the case of complementary circuits and/or in bipolar components, is very important.
There are certain places within the literature where the synthesis and the properties of phosphazenes are addressed. One example is the book “Superbases for Organic Synthesis—Guanidines, Amidines, Phosphazenes and Related Organocatalysts” by Tsutomo Ishikawa (WILEY, 2009, ISBN: 978-0-470-51800-7). This complex of topics is also treated, for example, in Núñez et al., J. Org. Chem. 1996, 61, 8386, which includes a description of the synthesis of hexaimida-zolylcyclotriphosphazene. There is no statement made concerning the fields of use of these substances within organic electronics.
Within the patent literature, the use of specifically substituted phosphazenes in organic electronics as electron conductors is mentioned. For example, WO 2009/153276 A1 discloses an organic light-emitting diode containing at least one cyclic phosphazene compound of the following formula
a light-emitting layer composed of at least one matrix material and at least one emitter material, the at least one matrix material comprising at least one cyclic phosphazene compound, the use of cyclic phosphazene compounds in organic light-emitting diodes, and a device selected from the group consisting of stationary screens, mobile screens, and lighting units comprising at least one organic light-emitting diode of the invention and selected cyclic phosphazene compounds, and methods for their production.
WO 2012 175219 A1 discloses an electronic device which comprises a compound A-B, where
in which —Ar1 is a C6-C18 arylene, which may be mono- or polycyclic and may optionally be substituted by one or more C1-C10 alkyl or C3-C10 cycloalkyl groups, —Ar2 is a C6-C18 arene skeleton which is optionally substituted by electron-donating groups R4, —B1 and B2 independently are selected from B and Ar2, —B3 is selected independently from the same group as B, —R1, R2 and R3 independently are selected from alkyl, arylalkyl, cycloalkyl, aryl and dialkylamino, —X is selected from 0, 1, 2 and 3, where for x>1 each Ar1 may be different, —y is a nonzero integer up to the total number of valence sites, on the arene skeleton, —z is an integer from zero up to the total number of valence sites on the arene skeleton minus y, and also a corresponding compound of formula AB.
The use of specifically substituted aminophosphazenes as n-dopants for increasing the conductivity of organic electron conductors, and not as electron conductors themselves, on the other hand, is not suggested by the prior art.